Get disk usage

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The annotation readOnlyHint=true already indicates safety, and the description adds that the tool returns specific disk metrics. However, no additional behavioral details (e.g., authentication needs, side effects) are disclosed. With annotations covering the safety profile, the description adds moderate context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, well-structured sentence that directly states the tool's function and outputs. No extraneous information, and the key details are front-loaded. Every word earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple, parameterless tool with no output schema, the description provides sufficient context about what data is returned. While it could optionally include units or format hints, it is complete enough for an agent to understand the tool's purpose and output.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has no parameters, and the input schema coverage is effectively 100% (empty schema). The description adds value by listing the returned fields (included, purchased, used bytes, monthly cost), which goes beyond the schema. Baseline 4 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states that the tool retrieves the authenticated account's disk state, specifying the exact data returned (included, purchased, used bytes, monthly cost). The verb 'Get' and resource 'disk state' are specific, and the tool is distinct from sibling tools like get_usage and get_credits, which cover different domains.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

No explicit guidance on when to use this tool vs alternatives is provided, but the tool's simple read-only nature and the sibling list (mostly agent-related tools) imply it's for checking disk usage. The lack of when-not-to-use or alternative suggestions keeps it from a higher score.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.